چكيده به لاتين
Nowadays, with the development of technology, the methods of manufacturing parts have changed, the purpose of which is to reduce manufacturing time, increase accuracy, and reduce waste and production costs. 3D printing technology is one of the pioneers of this field, which has grown and expanded a lot in the last decade. Therefore, in this research, the mechanical properties and fracture behavior of polymer parts made with PLA and PLA+CF (carbon fiber) filaments through the FDM method, which is one of the three-dimensional manufacturing methods have been investigated. After printing 48 SCB samples, tensile testing was done by the DIC method and three-point bending to determine the mechanical properties and failure of the parts. The angle of raster angle as one of the manufacturing parameters is (0/90) degrees, (15/-75) degrees, (30/-60) degrees, and (45/-45) degrees, and the crack angles are 0, 15, 30, and 40 degrees. The results within the parts were created to investigate the failure resistance in mode I and II with different printing lines. Then, SEM images of the fracture surfaces of the dogbones were done to determine the failure mechanisms in the presence of carbon fibers. The criterion used to calculate the numerical failure load for PLA material is the combination of two criteria, the concept of equivalent material and J-integral. And also, the J-integral criterion is considered for samples printed with PLA CF. The electrical conductivity test is also carried out to measure the printed samples' conductivity. The results have shown that the mechanical properties and fracture behavior are strongly dependent on the number of carbon fibers in the parent material. The high amount of carbon fibers inside the parts has reduced the resistance to failure, which is due to the concentration of high stress instead of resistance to failure, and if a material with a low percentage of carbon fibers is produced, there is a possibility that it can better withstand the tensile load. From other points, it is possible to mention the increase in the electrical conductivity of PLA CF, but the non-conductive parts are still considered and the conductivity is very small compared to nanocarbon.
